1/*
2 * Copyright (C) 2008 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17/*
18 * System utilities.
19 */
20#ifndef LIBDEX_SYSUTIL_H_
21#define LIBDEX_SYSUTIL_H_
22
23#include <sys/types.h>
24
25/*
26 * System page size.  Normally you're expected to get this from
27 * sysconf(_SC_PAGESIZE) or some system-specific define (usually PAGESIZE
28 * or PAGE_SIZE).  If we use a simple #define the compiler can generate
29 * appropriate masks directly, so we define it here and verify it as the
30 * VM is starting up.
31 *
32 * Must be a power of 2.
33 */
34#ifdef PAGE_SHIFT
35#define SYSTEM_PAGE_SIZE        (1<<PAGE_SHIFT)
36#else
37#define SYSTEM_PAGE_SIZE        4096
38#endif
39
40/*
41 * Use this to keep track of mapped segments.
42 */
43struct MemMapping {
44    void*   addr;           /* start of data */
45    size_t  length;         /* length of data */
46
47    void*   baseAddr;       /* page-aligned base address */
48    size_t  baseLength;     /* length of mapping */
49};
50
51/*
52 * Copy a map.
53 */
54void sysCopyMap(MemMapping* dst, const MemMapping* src);
55
56/*
57 * Map a file (from fd's current offset) into a shared, read-only memory
58 * segment that can be made writable.  (In some cases, such as when
59 * mapping a file on a FAT filesystem, the result may be fully writable.)
60 *
61 * On success, "pMap" is filled in, and zero is returned.
62 */
63int sysMapFileInShmemWritableReadOnly(int fd, MemMapping* pMap);
64
65/*
66 * Map part of a file into a shared, read-only memory segment.
67 *
68 * On success, "pMap" is filled in, and zero is returned.
69 */
70int sysMapFileSegmentInShmem(int fd, off_t start, size_t length,
71    MemMapping* pMap);
72
73/*
74 * Create a private anonymous mapping, useful for large allocations.
75 *
76 * On success, "pMap" is filled in, and zero is returned.
77 */
78int sysCreatePrivateMap(size_t length, MemMapping* pMap);
79
80/*
81 * Change the access rights on one or more pages.  If "wantReadWrite" is
82 * zero, the pages will be made read-only; otherwise they will be read-write.
83 *
84 * Returns 0 on success.
85 */
86int sysChangeMapAccess(void* addr, size_t length, int wantReadWrite,
87    MemMapping* pmap);
88
89/*
90 * Release the pages associated with a shared memory segment.
91 *
92 * This does not free "pMap"; it just releases the memory.
93 */
94void sysReleaseShmem(MemMapping* pMap);
95
96/*
97 * Write until all bytes have been written.
98 *
99 * Returns 0 on success, or an errno value on failure.
100 */
101int sysWriteFully(int fd, const void* buf, size_t count, const char* logMsg);
102
103/*
104 * Copy the given number of bytes from one fd to another. Returns
105 * 0 on success, -1 on failure.
106 */
107int sysCopyFileToFile(int outFd, int inFd, size_t count);
108
109#endif  // LIBDEX_SYSUTIL_H_
110